1. Field of the Invention
The present invention relates to a method of extracting ginsenoside Rg2, a pharmaceutical composition comprising ginsenoside Rg2 as an active ingredient, and prophylactic and therapeutic agents for preventing and treating dementia, depression, peripheral circulation disorder, and related diseases, utilizing the same.
2. Description of the Related Art
Ginseng contains various ginsenosides (ginseng saponins) and there are around 30 kinds of ginsenosides which have been known hitherto. Among these, ginsenoside Rg2 is a substance belonging to protopanaxatriol glycoside which was isolated and named a long time ago.
It is known through previous research and study that, in the course of red ginseng processing, a glycosidic bond at the C-20 position of ginsenoside Rg2 is readily susceptible to hydrolysis and at the same time, hydroxyl radicals lead to anti-equilibrium, i.e., breakdown of an equilibrium state, thereby forming a ginsenoside isomer C-20(S) or C-20(R). In addition, it is generally published that red ginseng contains mixed-type ginsenoside Rg2 C-20(RS) in a substantially higher content than fresh ginseng or white ginseng.
Meanwhile, since medical use of such ginsenoside Rg2 is as yet unknown, extracting and separating Rg2 has been conventionally carried out, on a laboratory-scale, by extracting ginseng total saponin (GTS) with an organic solvent, and separating ginsenoside Rg2 via silica gel column chromatography or high performance liquid chromatography (HPLC).
Firstly, a silica gel column chromatography process refers to a method involving adsorbing the ginseng total saponin extracts on a silica gel chromatography column, and separating ginsenoside Rg2 therefrom using the organic solvent, in which chloroform, methyl alcohol, ethyl acetate and water are mixed in a predetermined ratio, as a washing agent.
In this connection, the separation method utilizing the above-mentioned silica gel column chromatography mainly suffers from disadvantages such as trace amounts of substance of interest separated from the column, very slow separation speed, a need for an additional separation process due to use of a large quantity of harmful organic solvents, and being unsuitable for large scale production due to high production costs, low yield and unsafety.
Whereas, high performance liquid chromatography (HPLC) enables separation of high-purity ginsenoside Rg2, but presents problems such as high equipment and operation costs and increased production costs associated with use of a large quantity of expensive organic solvents such as methyl alcohol or acetonitrile. Consequently, conventional methods of separating ginsenoside Rg2 are not suitable for mass production of Rg2, thus making it expensive and difficult to enter practical commercial products.
That is, a process suitable for industrial-scale production is preferred to satisfy requirements such as simple and convenient manipulation and processes, easy practical application, high yield and purity, and harmlessness and safety to humans. In spite of such circumstances, research into such a desired process is insignificant.
Meanwhile, there are few published studies and investigations into medicinal usage of ginsenoside Rg2 and application thereof. Even though the present inventors have proposed medical use of ginsenoside Rg2, in Chinese Patent No. ZL01102117.9, entitled “Application of ginsenoside Rg2 in preparation of a therapeutic drug for cardio- and cerebrovascular diseases (CCVD), use of this therapeutic drug is restricted only to treatment of cardio- and cerebrovascular diseases such as myocardial ischemia, cerebral ischemia and shock diseases. As such, there is a need in the art for more advanced and improved research into new medical uses of ginsenoside Rg2.